Generally stated, skin functions to shield internal tissues from the environment and to protect against infection. Many implantable artificial organs and foreign devices require skin penetration which can disrupt the protective barrier typically provided by the skin under natural conditions. Percutaneous access devices (PADs) permit long-term skin penetration that allows access to and/or a connection between the interior of the body and an external device.
One common problem associated with PADs, implanted on a long-term basis, is that the bio-sealing connection between the skin and the device can be weak and not sufficiently strong to be able to resist detaching or fracturing during the stress introduced onto the skin during normal life activities. Unfortunately, a break in the bio-seal connection can lead to soft tissue infection and other complications. For example, epidermal cells can migrate and skin downgrowth can occur in an attempt to expel the foreign device from the body. Marsupialization may result wherein the skin surrounding the device forms a pocket and spontaneously expels the device. Alternatively, sinus tracts may form when marsupialization is incomplete and/or deep tissue infection may occur.
In the past, many designs for PADs have been proposed. Certain of these devices have used flanges to help hold the device in the body. However, and unfortunately, the configuration or location of the flange typically limited its ability to provide suitable connective assistance. For discussion purposes, disregarding the use of flanges on conventional PADs, the conventional PADs may be divided into two types: a flat connecting structure (FCS); and an anchored connecting structure (ACS). Both FCS and ACS type PADs can produce bio-sealing connections in tissue with bio-adhesive factors present in blood and other body fluids, to help interconnect the device and the tissue. Generally stated, the primary difference between the FCS and the ACS devices is that the FCS has a relatively limited or basic connecting surface area while the ACS has a larger connecting surface area, which can be a rough surface structure. As such, many of the ACS devices are able to form stronger bio-sealing connections than FCS devices. Unfortunately, each of these types of devices may cause infection, skin downgrowth, and other complications. Further, the bio-sealing connections proposed by these conventional PADs may be too weak to maintain the integrity of the bio-sealing connection during normal life activities, particularly when implanted for chronic or long-term indwelling periods of time.
In view of the foregoing, there remains a need for improved infection resistant support structures for securing devices to tissue.